LFCS Essential Commands Practice Test 4 — 15 Questions

Question 1

A security auditor needs to display the last 15 lines of /var/log/secure and then keep watching the file for new entries as they are appended. Which command should be used?

Accepted Answer

tail -n 15 -f /var/log/secure. Monitoring a growing log while seeing recent history is exactly what tail does with the -n and -f flags combined. tail -n 15 -f first prints the final 15 lines and then blocks, emitting new lines as they are written. head, cat, and less do not provide the same combination of tail-limited initial output and continuous follow.

Answer

cat -f /var/log/secure

Answer

head -n 15 /var/log/secure

Answer

less +F /var/log/secure

Question 2

A Linux administrator must archive the directory /home/project into a gzip-compressed tar file named project_backup.tar.gz, preserving permissions and excluding any files with a .tmp extension. Which command should be used?

Accepted Answer

tar -czf project_backup.tar.gz --exclude='*.tmp' /home/project. The tar command with -czf creates a gzip-compressed archive. The --exclude option filters out files matching the pattern. By default, tar preserves permissions and ownership in the archive metadata. The correct syntax includes the directory path without a trailing slash to ensure the directory itself is stored, and uses gzip compression as requested.

Answer

tar -czf project_backup.tar.gz --exclude='*.tmp' /home/project/

Answer

tar -czf project_backup.tar.gz --exclude='*.tmp' /home/project/*

Answer

tar -cjf project_backup.tar.gz --exclude='*.tmp' /home/project

Question 3

A system administrator needs to create a symbolic link named /usr/local/bin/editor that points to /opt/editors/vim9/bin/vim. The link must be created even if a file or link named /usr/local/bin/editor already exists, replacing it. Which TWO commands achieve this? (Choose two.)

Accepted Answer

ln -sfn /opt/editors/vim9/bin/vim /usr/local/bin/editor. Both accepted commands include -s to create a symbolic link and -f to remove any pre-existing destination before linking. The -n flag in the second accepted form additionally prevents ln from dereferencing a destination that is a symlink to a directory, ensuring the link is replaced at the intended path. The other choices either refuse to overwrite, create a hard link, or leave a backup copy behind.

Answer

ln -s -b /opt/editors/vim9/bin/vim /usr/local/bin/editor

Answer

ln -s /opt/editors/vim9/bin/vim /usr/local/bin/editor

Answer

ln -f /opt/editors/vim9/bin/vim /usr/local/bin/editor

Question 4

An administrator must copy the entire directory tree /data/reports to /archive/reports, preserving permissions, timestamps, symbolic links, and extended attributes, and must be able to resume an interrupted transfer. Which TWO commands or options accomplish this? (Choose two.)

Accepted Answer

cp -a /data/reports /archive/reports. Preserving the full metadata set including extended attributes and ACLs requires tools aware of those structures. rsync with -aHAX and --partial covers permissions, timestamps, symlinks, hard links, ACLs, xattrs, and resumability in one command. cp -a preserves metadata but lacks resume support. The other commands either move data, mishandle directories, or omit required preservation features.

Answer

scp -r -p /data/reports /archive/reports

Answer

dd if=/data/reports of=/archive/reports bs=4M

Answer

mv /data/reports /archive/reports

Question 5

A database administrator needs to extract only the 'CREATE TABLE' statements from a large SQL dump file 'schema.sql'. The statements span multiple lines and end with a semicolon. Which command should they use?

Accepted Answer

awk '/CREATE TABLE/,/;/' schema.sql. awk's range pattern /start/,/end/ prints all lines from a line matching start through the next line matching end. For SQL statements, this captures the full CREATE TABLE block including the terminating semicolon. Other tools either limit to a fixed number of lines or have syntax issues, making awk the most reliable choice.

Answer

grep -A 1 'CREATE TABLE' schema.sql

Answer

sed -n '/CREATE TABLE/,/;/p' schema.sql

Answer

perl -ne 'print if /CREATE TABLE/../;/' schema.sql

Question 6

An administrator needs to extract the contents of a gzip-compressed tar archive named backup.tar.gz into the current directory. Which TWO commands will accomplish this? (Choose two.)

Accepted Answer

tar -xzf backup.tar.gz. The tar command with -xzf extracts a gzip-compressed archive. Adding -v simply provides a verbose listing during extraction, which does not alter the outcome. Both commands correctly decompress and extract the archive into the current directory. Other options either use the wrong compression type, change the target directory, or rely on an incorrect gzip invocation.

Answer

tar -xjf backup.tar.gz

Answer

gzip -d backup.tar.gz | tar -xf -

Answer

tar -xzf backup.tar.gz -C /tmp

Question 7

An administrator is preparing a shell script that must safely create a nested directory tree under /srv and then confirm the result. The script must (1) create parent directories automatically if they do not exist, (2) avoid failing if the target directory already exists, and (3) print a message describing each directory as it is created. Which three commands or command fragments accomplish these goals? (Choose three.)

Accepted Answer

mkdir --parents --verbose /srv/app/logs. The --parents (or -p) option makes mkdir create missing intermediate directories and succeed when the target already exists, while --verbose (or -v) prints a line for each directory actually created. Using them together, either in short or long form, produces an idempotent, self-reporting command that satisfies all three script requirements in one invocation.

Answer

mkdir -m 755 /srv/app/logs

Answer

mkdir -Z /srv/app/logs

Question 8

A user reports that a script fails with 'Permission denied' when executed. The script has permissions -rw-r--r-- and is owned by the user. Which command should the user run to make the script executable for the owner only?

Accepted Answer

chmod u+x script.sh. The script currently has permissions `-rw-r--r--`, meaning the owner has read and write but not execute permission. The `chmod u+x` command adds the execute permission for the owner only, which is exactly what the user needs to run the script without affecting group or others.

Answer

chmod u+s script.sh

Answer

chown :users script.sh

Answer

chmod +x script.sh

Question 9

A system administrator needs to find all files in /var/log that have been modified in the last 7 days. Which command accomplishes this?

Accepted Answer

find /var/log -type f -mtime -7. The `find` command with `-mtime -7` searches for files whose modification time (content change) is less than 7 days ago, which matches the requirement of 'modified in the last 7 days'. The `-type f` restricts the search to regular files, and `/var/log` is the target directory.

Answer

find /var/log -type f -atime -7

Answer

find /var/log -type f -ctime -7

Answer

find /var/log -type f -mtime +7

Question 10

A user wants to find the location of the 'grep' binary. Which command should they use?

Accepted Answer

which grep. The 'which' command is specifically designed to locate the binary (executable) of a command by searching the directories listed in the user's PATH environment variable. Option B, 'which grep', will output the full path to the grep binary, such as '/usr/bin/grep', directly answering the user's request.

Answer

man grep

Answer

uname -a

Answer

grep -r 'grep' /usr/bin

Question 11

Which THREE commands can be used to view the contents of a file?

Accepted Answer

cat. The `cat` command (option C) is a standard Unix utility that reads files sequentially and outputs their contents to the standard output. It is one of the most basic and direct ways to view the entire content of a file in the terminal.

Answer

grep

Answer

find

Question 12

What is the purpose of the chmod 755 command in this exhibit?

Accepted Answer

Set permissions to rwxr-xr-x. The chmod 755 command sets the file permissions to rwxr-xr-x, meaning the owner has read, write, and execute permissions (7), while the group and others have read and execute permissions (5). This is a common permission set for executable scripts and directories to allow execution without granting write access to non-owners.

Answer

Add execute permission for the owner only

Answer

Remove write permission for others

Answer

Set the setuid bit

Question 13

Based on the exhibit, which process will be affected if the root user runs 'kill 5678'?

Accepted Answer

The www-data process with PID 5678. The 'kill 5678' command sends the default SIGTERM (signal 15) to the process with PID 5678. Since the root user has the CAP_KILL capability and is not subject to the ordinary permission checks that restrict non-root users, root can send signals to any process, including those owned by www-data. Therefore, the www-data process with PID 5678 will be terminated.

Answer

The root process (PID 1234)

Answer

All www-data processes

Answer

No process, because root cannot kill www-data processes

Question 14

A junior administrator needs to display the first 10 lines of a file named 'data.csv'. Which command should they use?

Accepted Answer

head data.csv. The `head` command is specifically designed to display the first 10 lines of a file by default. Running `head data.csv` will output the first 10 lines of the CSV file, making it the correct choice for this task.

Answer

less data.csv

Answer

tail data.csv

Answer

cat data.csv

Question 15

Which TWO commands can be used to display the current working directory? (Choose exactly two.)

Accepted Answer

echo $PWD. The shell stores the current working directory path in the environment variable `$PWD`, and `echo $PWD` prints its value. This is a reliable way to display the current directory, as the shell updates `PWD` automatically on every `cd` command.

Answer

ls

Answer

dirname

Answer

cd